Experimental study on supporting status of internal and external loading of two-legs shielded hydraulic support

In order to solve the problem that the internal loading can not reflect the real working condition of the hydraulic support and the lack of test basis for the intelligent mining support state regulation,a 1∶2 scaling model of ZY6400/17/31 was developed, and the monitoring system for displacement and pressure were established. The system adopts internal and external loading modes respectively, and tests the hydraulic supports under different contact conditions of the blocks according to GB 25974.1-2010.The results shows that the point of resultant force of the internal loading and the external loading force is easy to offset and the response of the hydraulic support is obvious. The former shows the pressure synergy and the latter acts the displacement synergy; the balance jack is under the unregulated external loading state. The number of loading will have a cumulative effect, resulting in increasing pressure and instability tendency. The contact state has a great influence on the displacement of the column. Therefore, the posture must be measured at the underground site to provide a basis for judging the contact state of the surrounding rock between the top and bottom plates.